This specification relates to storing data.
Typical systems allow for the storage of multiple versions of a data item (e.g., versions of a file stored in a backup). In some conventional systems, these versions are stored according to the location of the data item in a hierarchical file system, for example, within the file system hierarchy of a local device or in a backup that mimics the file system hierarchy. Thus, storing a version typically requires storing the entire file system directory path. Conventionally, all versions of the data item have the same permissions as the permissions of the current data item.